Secondary batteries, which can be recharged repeatedly, are used as batteries for many portable information devices. Battery degradation prevention, long time power supply, miniaturization, and low cost are important factors for secondary batteries. In a conventional lithium-ion battery pack, for example, a built-in protection circuit module with a protection circuit is provided. Such a protection circuit prevents battery degradation caused by excessive heat generated by overcurrent resulting from short circuit, incorrect charging (overvoltage or reverse voltage), or any other cause.
For example, a conventional protection circuit is implemented by inserting current control transistors composed of MOS transistors in series in a charge-discharge circuit, i.e. between a secondary battery and an external connection terminal to which a battery charger or a load is connected. When abnormal charging is detected, a current control transistor for charge control is turned off to stop the charging; when an abnormal discharging is detected, a current control transistor for discharge control is turned off to stop the discharging (see, for example, patent document 1).
FIG. 8 is a circuit diagram illustrating an exemplary secondary battery protection circuit module.
In FIG. 8, a secondary battery 48 is connected between battery-side external terminals 44a and 44b, an external apparatus 50 is connected between load-side external terminals 46a and 46b, the battery-side external terminal 44a and the load-side external terminal 46a are connected by a plus-side charge-discharge circuit 52a, and the battery-side external terminal 44b and the load-side external terminal 46b are connected by a minus-side charge-discharge circuit 52b. A current control transistor 54 and a current control transistor 56 are connected in series in the charge-discharge circuit 52b. The current control transistors 54 and 56 are composed of field effect transistors.
A protection integrated circuit (IC) chip 58 is connected between the charge-discharge circuits 52a and 52b. A supply voltage terminal 58a of the protection IC chip 58 is connected via a resistance element 60 to the charge-discharge circuit 52a; a ground terminal 58b is connected to the charge-discharge circuit 52b at a point between the battery-side external terminal 44b and the current control transistor 54; and a battery-charger minus-potential input terminal 58c is connected via a resistance element 62 to the charge-discharge circuit 52b at a point between the load-side external terminal 46b and the current control transistor 56. A condenser 64 is connected between the supply voltage terminal 58a and the ground terminal 58b. An overdischarge detection output terminal 58d is connected to the gate of the current control transistor 54. An overcharge detection output terminal 58e is connected to the gate of the current control transistor 56.
A PTC element 66 is connected between the battery-side external terminal 44b and the secondary battery 48.
In a conventional protection circuit module having a protection circuit as described above, packaged components are used as semiconductor components such as the current control transistors 54 and 56 and the protection IC chip 58, and are mounted on the circuit board.
However, since a semiconductor chip and leads are connected by bonding wires in such a packaged component, the cost of such a packaged component is high. This high cost is one of the disadvantages of using packaged components. Also, since the semiconductor chips in packaged components used as the current control transistors 54 and 56 are electrically connected via bonding wires and leads to the circuit board, it is difficult to lower on-resistance.
To solve problems described above, a protection circuit module produced by using the chip on board (COB) technology has been proposed (see, for example, patent documents 2 and 3). In the COB technology, a bare chip is mounted on a circuit board and electrodes of the chip and the circuit board are electrically connected via bonding wires.
However, since gold is used as the material of bonding wires, it is still difficult to substantially reduce the cost of a protection circuit module with the COB technology. Also, since the semiconductor chips used as current control transistors in such a protection circuit module are electrically connected via bonding wires to the circuit board, it is difficult to lower on-resistance.
Another packaging technology called the flip chip packaging technology has been proposed (see, for example, patent document 4). In the flip chip packaging technology, a bare chip having multiple external connection terminals arranged on a surface is mounted on a circuit board upside down. A secondary battery protection circuit module produced by using the flip chip packaging technology has been proposed (see, for example, patent document 5). In such a secondary battery protection circuit module, semiconductor components including a protection IC chip and current control transistors are mounted on a circuit board upside down.
The flip chip packaging technology for mounting semiconductor components on a circuit board can make production costs lower than those necessary when the wire bonding technology is used. Also, the flip chip packaging technology requires a smaller mounting area for a semiconductor component. Further, with the flip chip packaging technology, it is possible to reduce the on-resistance of field effect transistors.
In an electrical characteristics test of an electronic component device such as a secondary battery protection circuit module, the electronic component device may be either on a collective circuit board where multiple electronic component devices are arrayed before being diced into separate circuit boards or on a separate circuit board cut out from such a collective circuit board.
In such an electrical characteristics test of an electronic component device, an electronic component device testing apparatus is used to electrically connect a tester for sending a test signal to the electronic component device and the electronic component device.
FIG. 9 is a cross-sectional view of an exemplary conventional electronic component device testing apparatus.
In the exemplary conventional electronic component device testing apparatus, a socket 72 for holding pogo pins 74 is attached to a base 70 such as a testing board. Multiple pogo pins 74 are arrayed in the socket 72.
Each of the pogo pins 74 includes an electronic-component-device-side pin 74a positioned at one end of the pogo pin 74 closer to an electronic component device 98 and a base-side pin 74b positioned at the other end of the pogo pin 74 closer to the base 70. The electronic-component-device-side pin 74a and the base-side pin 74b are electrically connected inside the pogo pin 74.
Base electrodes 76 are formed on the base 70 in positions corresponding to the positions of the pogo pins 74. The base electrodes 76 are connected by a wiring pattern (not shown) to connectors (not shown) for outputting electric potentials of the base electrodes 76 to the outside. The base-side pins 74b of the pogo pins 74 are in electrical contact with the base electrodes 76.
During an electrical characteristics test, the electrodes 99 of the electronic component device 98 are brought into electrical contact with the electronic-component-device-side pins 74a of the pogo pins 74. Electric power and test signals are supplied to the electrodes 99 via the base electrodes 76 and the pogo pins 74.
[Patent document 1] Japanese Patent Application Publication No. 2001-61232
[Patent document 2] Japanese Patent Application Publication No. 2002-141506 (page 2, page 4, FIGS. 2, and 3)
[Patent document 3] Japanese Patent Application Publication No. 2002-314029 (pages 2-3, FIGS. 14, and 15)
[Patent document 4] Japanese Patent Application Publication No. 10-112481
[Patent document 5] Japanese Patent Application Publication No. 2000-307052
[Patent document 6] Japanese Patent Application Publication No. 5-307069 (FIG. 4)
During an electrical characteristics test of the electronic component device 98, electric power and test signals are supplied to the electrodes 99 via the pogo pins 74 used as contacts. In the conventional electronic component device testing apparatus described above, the resistance of the pogo pins 74 has been a problem, often preventing an accurate test of the electronic component device 98.